Reference may be made to the following U.S. patents of interest concerning mechanical flexure elements: 4,748,858; 3,638,481; 3,370,458; 3,151,693; 3,848,462; 2,963,904.
In many applications, it is desired to provide a flexure element that can be used to amplify or increase small motions into larger motions. One example of such a desirable use for such a device is in instrumentation where for example a sensing element is subjected to or undergoes a slight displacement which is to be detected to provide a motion indication or a quantitative motion measurement. Such motion amplification devices are extremely desirable for example for use with piezoelectric, magnetostrictive, or electrostrictive elements, and other such types of transducers in the detection or sensing of very small displacements in the micron range, i.e., micro-meter range.
Present motion amplification devices such as lever mechanisms suggested for micro-meter range sensing have major drawbacks in certain areas such as reaction to temperature changes, fragile structure, low motion amplification, high lost motion characteristics, high hysteresis losses, or costly materials or method of manufacturing. Accordingly, it is desired to provide a mechanical flexure which can be sized to amplify very small, micron displacements generated for instance by magnetostrictive, electrostrictive and piezoelectric elements, so as to be adaptable for use in practical actuator and transducer units and which desirable flexure element provides the following advantages over conventional lever mechanisms: (1) simple, low-cost structure and method of manufacture; (2) providing high amplification ratio for very small displacements; (3) significantly reduced lost motion characteristics; (4) very linear for small displacements; (5) low hysteresis; (6) low sensitivity to temperature changes; and (7) rugged, reliable structure with long lasting performance.
Reference may also be made to the following U.S. patents of interest with respect to electromechanical transducers: 4,701,660; 4,158,368; 4,025,942; 3,370,458; 3,218,445; 2,992,373; 2,904,735; 2,769,867; 2,419,061; and to the publication, "Application Manual For The Design of Etrema TERFENOL-DTM Magnetostrictive Transducers", J. L. Butler, Edge Technologies, Inc. 1988.
Electromechanical transducers have been used for many years to transform, for instance, electrical signals into a mechanical motion, and vice versa. Such transducers find application in a variety of circumstances, including fluid flow control devices, fluid flow indicating and measuring devices, etc. A particular need is desired for a reliable electromechanical transducer which can respond to very small electrical signals to provide micro-motion in a transducer element or a moving member connected to the transducer element. Prior electromechanical transducers have utilized piezoelectric substances, Rochelle salt, or electrostrictive materials, such as polycrystalline ceramics.
Recently, in the desire to obtain more sensitive and faster acting electromechanical transducers, the introduction of magnetostrictive materials to such transducers has been proposed, such as is disclosed in the above indicated U.S. Pat. No. 4,158,368. This patent proposes the use of a magnetostrictive material with coupled members movable by the magnetostrictive material when placed in a magnetic field. Several embodiments are illustrated in this patent including, a valve plunger, a plate having apertures in another valve configuration, and two sliding plates with apertures selectively alignable in another valve configuration.
It is desirable to provide an electromechanical transducer for sensing and producing micro-motions in a more simple structural and operating configuration compared to prior suggested devices.